It's late & I'm not to sure of my math - help?

MurrayMinchin

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It's late...my mind has turned to mush...what small bit of my brain capable of juggling numbers is now a twitching and shrunken knot. Does the following line of logic make sense?

I just got a gallon of ammonium thiosulfate in a 60% solution to mix up some TF-3 fixer. The original recipe calls for 800ml of the ammonium thiosulfate to go into 1000ml of stock solution (S.S.), which when mixed 1:4 makes 5000ml of working solution (W.S.).

One problem is that a gallon (US) equals 3800ml, and 800ml goes into 3800ml 4 times leaving 400ml left over. Another problem is that I keep my TF-3 in 4000ml mylar (actually aluminized plastic) wine bags, so 5000ml of W.S. isn't very helpful.

Enter the slippery slope of rationalization........

1000ml S.S. - 21% = 790ml S.S. that when mixed 1:4 = 3950ml W.S.
(good amount for the wine bags)

So the new recipe would be;

- Ammonium Thiosulfate.......800ml - 21% = 632ml
(632ml goes into 3800ml 6 times and leaves just 8ml left over)

- Sodium Sulfite (anhydrous)....80g - 21% = 63.2g

- Sodium Metaborate..................5g - 21% = 3.95g

- Water to make 790ml S.S. for 3950ml of W.S.

Make sense?

Murray
 

Troy Hamon

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Murray...I will point out to be pesky that 800 goes into 3800 4 times with 600 (not 400) left over...in case it matters...I bet this isn't the kind of help you were looking for...

As far as the other math...seems okay to me.
 
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MurrayMinchin

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Troy Hamon said:
...I will point out to be pesky that 800 goes into 3800 4 times with 600 (not 400) left over...
Click to expand...

D'OH!

Thanks Troy

Murray

P.S. Your darkroom looks sweet & I liked the kids table with the 'darkroom only' toys...very smart! Oh, and I still have your Aniakchat (sp?) images in my mind...I'll have to see that place one of these years.
 

johnnywalker

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Completely irrelevent to your question, but how do you fill the wine bags? In the old days (when I was a wino) the dispenser popped off, making them both easy to drink from and easier to re-fill. I tried it today on a new bag, and the dispenser is not meant to be disassociated with the bag. (I can use those big words these days). Perhaps the neighbour I stole it from is drinking the wrong version of Chateau Neuf de Porch Cimbair?
 

Ole

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Does the instructions say 1:4 or 1+4?

You write 1:4, but then go on to describe a 1+4 mix. A 1:4 would be 1 part concentrate plus three parts water for a total of 4 parts - problem solved!
 
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MurrayMinchin

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Hi Johnny...you're right in that most boxed wines are coming in clear bags now, and have a hard black plastic dispenser with a red button. (They suck). The ones I use have the large diameter, soft brown removable dispenser. (They're fun to suck).

To fill them, I lay the bag on its back and slide the bags spout into a 'keyhole' shape cut out of the bottom of an overturned (unused) plastic kitty litter tray. This holds the spout up, keeps the funnel steady, and makes it easier to get the dispenser back on. Afterwards, I open the dispenser a bit to push the air out of the bag.

You really have to get a lower class of neighbour who drinks budget wine

Murray

P.S. Hi Ole, in my world, mixing 1 litre of S.S. at 1:4 with water makes 5 litres of W.S....but then again, 3800 - 3200 sometimes = 400 :rolleyes:
 

Claire Senft

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I know the hazards of being up late. Here is how it works. If 2 hours ago it was 36 minutes after 11pm it is now 36 minutes after 1 am. See we work on 12 hour cycles. One cycle goes from midnight until noon. This is the am section which is found on the regular radio dial with the bigger numbers. From Noon until midnight it is pm, but on your radio dial it is the smaller numbers marked fm. Forgive me for stating the obvious but fm means "Fully Mooned".

Should I send you my listener's guide? My deafness makes the radio method less than fully useful to me so I am now using the analog approach called a clock. Even though I can no longer hear it ticking, I still get a general sense of what time it is.
 

jim appleyard

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If two trains leaving the station at 1am and one is moving at 20 km/hr faster, when do they reach their destination? I used to loathe those problems!
 

Ole

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MurrayMinchin said:
... P.S. Hi Ole, in my world, mixing 1 litre of S.S. at 1:4 with water makes 5 litres of W.S...
Click to expand...

I would always assume that 1:4 means that one quarter of the final volume is the first component. 1+4 means add one part A to four parts B, so that A is one fifth of the final volume.

It makes no difference at 1:100, but a LOT at 1:2!
 

Steve Smith

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I think I would agree with Murray and say that 1+4 is the same as 1:4

The colon indicates a ratio so 1:4 means a ratio of 1 part of something to four parts of something else giving a total of five parts.

It would be interesting to hear other peoples opinions on this because obviously, one is correct and the other is wrong - especially important, as Ole points out, when it is a small ratio.

Steve.
 

Helen B

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This discussion illustrates why using 1:x ought to be avoided for describing dilutions - it is ambiguous unless you also explain what the 'x' refers to. It could be water, it could be the mixed solution. '1+x' is unambiguous because the x can only be water, it can't be the mixed solution. Unless, of course, the train that left at 1 am has three oranges more than Derek.

Best,
Helen
 

colrehogan

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Here at work, we write 1:2, but when we do the actual mix, we mix 1 part A + 1 part B. The 2 in 1:2 is in reference to the total solution volume, A+B.
 
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MurrayMinchin

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From Ansel Adams book, "The Print";

"Thus one quart of stock mixed with three quarts water to make a gallon of 1:3 working solution..."

Murray
 

Kirk Keyes

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MurrayMinchin said:
From Ansel Adams book, "The Print";

"Thus one quart of stock mixed with three quarts water to make a gallon of 1:3 working solution..."
Click to expand...

Yeah, unfortunately Ansel was not a scientist where these two systems of notation have very distinct meanings.

Follow Helen and Ole's advise when working with these short-hands.
 

Steve Smith

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Yes, I suppose if you think of it as a ratio of something to the total quantity it makes sense.

Thinking I have been getting it wrong, I looked up Ilford's dilution data and was please to see they put it in 1+9, 1+14 terms instead of 1:9, 1:14

The 1+9 dilution makes things really easy as it is 10% of total so if you need 600ml of solution you put in 10% or 60ml of developer (fix, etc.) and top up to 600ml.

I have not looked at other manufacturers' data but I hope they use + instead of : as it is less ambiguous. Especially as a lot of us will say one to four when it is actually written 1+4.


Steve
 
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MurrayMinchin

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From the label on the back of a bottle of Kodak rapid selenium toner;

"For tone change, dilute 1 part toner with 3 - 19 parts water. To enhance D-max and protect image, dilute 1:20 - 1:40".

Murray
 

John McCallum

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Gotta admit, Ole and Kirk's posts came as a curve ball to me as well. I have always interpreted 1:4 to amount to total 5 in soln. The one thing I remember from systematic inorganic chemistry days other than Rachael Winklebottom.
Then again, maybe she is the only thing I remember correctly. Just shows how using the same ol' solns forever large ratios and adjusting the recipe and cooking time can cover up major errors.

Pls someone correct us if we're wayward...
 

Helen B

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The thing about Kodak literature in general is that they avoid ambiguity by explaining what the ratio means, just as with the example Murray quotes. The HC-110 data sheet says "Ratio of stock solution to water" and "Ratio of concentrate to water" for example. Now that might be taken as the common practice in photography and the explanation omitted but, as this thread shows, it isn't a universal practice. Another opportunity for miscommunication and error. What fun.

Best,
Helen
 

Paul.

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My maths is not great either, but I have always worked on 1+4 = a 5th part ie. 1+4=5,
1000ml divided by 5 =200ml
= 200ml of stock +800ml of water = 1lt of working solution.

I wonder if it makes a differance which continent we went to school on and how long ago it was? In my case a long time.

Regards Paul.
 
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MurrayMinchin

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Hi Paul,

Post #1! Welcome aboard APUG

Murray
 

blansky

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On the day I mix chemistry, I hire a mathematician from the local college to come in and do it.

A man has to know his limitations.

Michael
 
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MurrayMinchin

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blansky said:
On the day I mix chemistry, I hire a mathematician from the local college to come in and do it.

A man has to know his limitations.

Michael
Click to expand...

Sage advice, yet again.

I thought I was asking a simple question and then things spin off on a wild 1+2=3...1:2=2...1:2=3 debate. Trying to get 14,479 photographers to agree on any one method is like trying to herd cats!

Murray
 

Helen B

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blansky said:
On the day I mix chemistry, I hire a mathematician from the local college to come in and do it.

A man has to know his limitations.

Michael
Click to expand...

Michael,

Are the unions cool about that? The demarcation rules agreed between the International Brotherhood of Mathematicians and Allied Numerical Operatives, and the Union of Chemical Workers are perfectly clear, and would prohibit an IBMANO member from actually mixing the chemicals.

Sorry, but that's how it is.
Helen
 

blansky

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I had him delivered by the International Brotherhood of Teamsters so it should be cool.

Or else.

They always seem to have a way to iron out those little bumps in the road. So to speak.


Michael
 
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